Although the 1 TB drive enjoys a 16 MB vs. 8 MB cache and SATA 300 vs SATA 150 advantage, keep in mind that it also has a much slower, variable spinning speed: 5,400 - 7,200 RPM vs. the 10,000 RPM of the Raptor.
This slower spinning speed is mostly responsible for the drive's power consumption savings. Overall drive noise is also reduced because of this. During testing, I was not able to hear the drive over anything else in my case - but this is true for all of my hard drives, including the Raptor. The slower spinning speed will no doubt result in a cooler drive as well, which could go a long way to prolonging the life of the drive. Less heat means it will also work exceptionally well as an external hard drive in an enclosure.
The Western Digital GreenPower 1 TB drive also enjoys a lower price point than other 1 TB drives currently available. As of writing, the GP drive can be had for under $190 over at Geeks.com. Doing some quick math, this comes out to 19 cents a gig - very nice!
OCIA.net has awarded the Western Digital Caviar GP 1 TB SATA HDD our Seal of Approval.